With the increasing demands in apparatus engineering, the demands on the valves used therein also are increasing. In modern laboratories, for example, and in particular in the clinical area directly in the patient environment, the avoidance or reduction of noise pollution gains in importance more and more. Especially for the field of “media-separated” valves, as they are used e.g. in food, analysis, laboratory and medical technology, only few low-noise solutions do exist on the market.
For many of the above-mentioned applications, solenoid valves are the first choice from a technical point of view. They are designed for fast cycle duties and with a corresponding design are suitable for aggressive or neutral liquid and gaseous media in various temperature and pressure ranges. A solenoid valve usually comprises a magnetic armature (core) which is movable in one direction of movement by the force of an electromagnet and in the opposite direction by the force of a return spring. On energization of the electromagnet, the armature is accelerated from the starting condition by the magnetic field generated, until it reaches an end position specified by a limit stop, usually a metal plug. In the course of the switching path, the speed of the armature is increasing steadily. The magnetic force becomes the larger the closer the armature comes to the plug. At the end of the switching path, when the armature hits the plug, a distinctly perceptible clicking noise is heard, which mostly is perceived as disturbing, in particular when the switching frequency is high. Noise damping can be achieved by an elastomer element mounted on the plug or armature However, this measure leads to a reduced stroke of the armature and to a reduced driving force at the end of the stroke path.
In the above-mentioned field of the media-separated valves, a valve type which here briefly is referred to as “Lorentz valve” recently is establishing itself. In this valve type, which is known for example from WO 2010/066459 A1, an electrodynamic actuator is employed. On energization of a coil, a stationary magnet arrangement exerts a Lorentz force on the coil, which is utilized for deflecting a mechanically pretensioned control element. A prerequisite for this is that the coil is part of the movable control element. In contrast to a solenoid valve, the driving force in a Lorentz valve is linearly dependent on the current intensity, i.e. with constant current intensity the driving force remains constant. Such valve mostly is less noisy, because there is no impact of the control element on a metallic limit stop. On switching, however, a noise will yet be heard, when the control element or a tab of the control element hits a valve seat.